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Pluto Has Frozen 'Sand' Dunes

The pale gray and white ridges were revealed on a spacecraft flyby
By Newser Editors and Wire Services
Posted May 31, 2018 3:53 PM CDT
This July 2015 image made by the New Horizons spacecraft shows dunes, small ripples at bottom right, on Pluto's Sputnik Planitia ice plain. At upper left are a series of mountains.   (NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute via AP)

(Newser) – Scientists have discovered dunes on Pluto made of tiny frozen grains of methane, reports the AP. The pale gray and white ridges were revealed by NASA's New Horizons spacecraft during its 2015 flyby. A British-led team announced the findings Thursday in the journal Science. Researchers said the dunes appear to be made mostly of icy specks of methane the size of sand, with some frozen nitrogen likely mixed in. Thought to be relatively recent, the parallel rows of dunes are located in Pluto's heart-shaped region at the base of mountains as tall as the Alps and formed from giant blocks of ice with frosty methane snowcaps. These plains in the left lobe of Pluto's "heart" are known as Sputnik Planitia. Scientists were surprised to find dunes given Pluto's thin, weak atmosphere. They suggest nitrogen ice coating the surface of Sputnik Planitia transformed into gas that lifted methane particles into the air.

Pluto's gentle winds then carried and deposited the grains. Researchers liken the dunes to those at White Sands, New Mexico, or California's Death Valley. "It's a little bit lower density than sand we're used to holding on the Earth," a study co-author explains. "So it would feel lighter in your hand, but it would still be granular and would kind of flow off of your hand, and your feet would kind of crunch them as you're walking along. It would just kind of feel a lot like you're on another sand dune on the Earth." The team has yet to determine the height of the dunes; the lead author guesses they're at least tens of yards tall. Dunes have also been found on Mars, Venus, Saturn's moon, Titan, and even a comet. But Pluto's are the only ones known to consist of methane. "Pretty much nowhere else we know of is cold enough!" the study's lead author says.

(Read more Pluto stories.)

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